It’s a fact that when a vehicle sits for long periods the
tires flat spot. The reasons that tires flat spot are basically a function of
pressure, temperature and time. Flat spotting is either temporary, in that the
tire will round out with driving, or permanent which affects the belting and
casing of the tire. Permanent flat spots effectively ruin the tire. There are
no real indicators that tell when a temporary flat spot will become permanent.
TireCradles will prevent any type of flat spotting from occurring on your
Styrofoam (expanded polystyrene) and rubber mats both used by low cost knockoffs have been tried and failed. Comfort floor mats, carpet squares piled with carpet insulation or plywood, and layers of cardboard have been tried and failed. None of these options have worked! Our company began to look at the physics of tire flat spotting; how they are measured, what causes them, etc. and in the mid 1990s developed TireCradles based on that research.
Flat spots are measured using two criteria; peak to peak
changes and harmonics. No tire is perfectly round and the peak to peak changes
( P/P ) reflect how much pressure must be applied to the tire in downforce to
make the tire perfectly round. That is, you apply pressure at the axle while
the tire is rotating until the tire is perfectly round. A flat spotted tire
will increase this value by a minimum of about 4 psi. In our testing, this
value has more than doubled from the original value! The test showed a change
from 16.0 to 32.2 psi.
Temporary flat spots are simply rubber compression and they
go away as soon as the rubber warm and re-rounds. These are always either 1st
or 2nd harmonic flat spots. It is crucial to remember that all permanent flat
spots begin with a temporary flat spot. The only difference is how long the
vehicle stays parked. Harmonics are measured from 1 to 10 with ten being the
least case scenario. A first harmonic flat spot ( 1 ) means that for every
rotation of the tire, at any speed, the flat spot is felt. As such, you would
feel this going 22 mph or 122 mph.
A high harmonic flat spot, 6 or above, is often not
recognized as a flat spot but is often confused with a mechanical problem. This
is best explained as a particular speed where the problem manifest itself. An
example would be a car that has a shimmy or vibration from 66 to 70 mph but
none above or below that speed range. This is almost always a high harmonic
permanent flat spot.
We have seen cases where torque converters, clutch
assemblies and half shafts have been replaced trying to fix the problem; it is
almost always tire flat spotting. For the car owner, this is very time
consuming, personally frustrating, and expensive if the car is out of warranty.
Your tires are designed to operate in a wide variety of
temperatures. Most performance tires are designed to function best at triple
digit temperatures. While the rubber compounds offer the best performance at
these temperatures, flat spotting is also accelerated. What makes your tires
work also helps them to flat spot. Parking a hot, soft tire on a cool concrete
surface accelerates tire flat spotting because the contact patch is stressed by
the temperature and density differences. Basically, the tire must
"give" because it is softer and hotter than a concrete floor.
Tire construction also determines the tendency of a tire to
flatspot. Soft compounds and aspect ratios associated with performance tires
accelerate flat spotting. An aspect ratio of 50 or less has little sidewall
flexion due to the short sidewalls. Thus, the pressure is absorbed by the
contact patch and the tire flat spots. Basically, the wider the tire, the
greater its tendency to flatspot. Vehicle weight, time parked and ambient
temperature all factor in flatspotting your tires. TireCradles are designed to
prevent flat spotting on all road going tires by negating those variables. They
keep your tires insulated from the temperatures and pressures that cause flat
spotting, regardless of the amount of time a vehicle is parked.
TireCradles are made of a very dense, polyurethane polymer
and this polymer is very costly, but it is the only polymer that works for this
specific application. Think of it from this perspective, how many sets of tires
will you own in your lifetime and what is the cost of replacing a ruined
performance tire or tires? We think that you will agree that TireCradles are
really smart insurance. TireCradles will save you money in the long term
because you will be preserving and protecting your tires rather than replacing
them. It’s your car and your ride — you decide.